Remove unnecessary queries for network info in notifications
Remove unnecessary queries for network info in notifications

bandwidth_usage() tries to query network info if "not network_info"
when looking at instance['info_cache'].  [] is a valid entry for
network_info (on build)... so don't query network when we see it.

Fixes bug 1017770

Change-Id: Ia7291dbbcc25c04eff16eb048068f879e18f53a4

n0ano/gantt,n0ano/gantt